Contributions of Charge Generation Versus Transport to Photocurrent in Dilute-Donor Organic Solar Cells with Non-fullerene Acceptors

The photocurrent generation in dilute donor organic solar cells (DDOSCs) based on fullerene and non-fullerene acceptors is compared. The donor concentration is kept under 5 wt % to avoid the formation of a percolation pathway for hole transport, as verified by studying the hole mobilities in an insulating polymer matrix. The short-circuit current densities (Jsc) in DDOSCs for three common acceptors are quantified in terms of charge generation, transport, and collection, which are probed using ideal Jsc calculated from the transfer matrix method, hole mobility measured from space charge limited current method, and charge collection efficiency, respectively. Using non-fullerene acceptors improves both charge generation and transport, with charge transport being more important in determining Jsc in DDOSCs.